### - o -

- ooc : solver_option
- op : apply_iterator< Iterator, Operator >
- option : family_index_option_type
- order : geo_element::parameter_type , geo_header , gmsh_element_t
- orient : side_information_type
- orient_mask : geo_element_indirect
- orient_position : geo_element_indirect
- origin : render_option
- ownership : MeshType
- ownership_by_dimension : geo_size
- ownership_by_variant : geo_size